Live-cell imaging chambers have played a critical role in recent cell biology research. A variety of designs for such chambers have been made since mammalian cell culture techniques were developed in the early twentieth century. These designs vary in complexity from simply covering specimen on a microscope slide with a coverslip to sophisticated perfusion chambers that enable living specimens to remain viable for a significant length of time outside the incubator. At present, a variety of chambers for taking high resolution and time-lapse images of live cells using phase contrast, differential interference contrast (DIC) and fluorescence microscopy are commercially available.
The basic design of most live-cell imaging chambers consists of a sandwich structure made from two transparent plates separated by a rubber O-ring or similar spacer and a holder that can be made from a variety of different materials and houses the sandwich structure. Various modified versions of this basic design have also been manufactured in recent years. To keep cells viable in a live-cell imaging chamber for a prolonged period of time, the cells in the chamber need to be kept in an environment that has a regulated temperature, to be maintained a constant pH, to be provided with sufficient O2 and also to be supplied with an adequate energy supplies. The designs used to control the temperature of a live-cell chamber adequately include a Peltier heat pump, resistive coils, circulating warm water, circulating warm air, a climate controlled box, a stage warmer and an objective-lens heater with indium-tin oxide coated glass (Rieder C. L. and Cole R. W. 2002. Cold-Shock and the Mammalian Cell Cycle. Cell Cycle 1: 169-175.). Fresh medium at the preferred pH range and containing sufficient O2 and energy supplies typically flows through the chamber and is driven by gravity, a peristaltic pump or a syringe pump (Rieder C. L. and Cole R. W. 2002. Cold-Shock and the Mammalian Cell Cycle. Cell Cycle 1: 169-175.).
A change in temperature has profound influences on the physiology of cells. Cold and heat stress may affect gene expression, immune function and the cell cycle (Sonna L. A. et al., 2002 Molecular Biology of Thermoregulation Invited Review: Effects of heat and cold stress on mammalian gene expression. J appl Physiol 92: 1725-1742.). At a molecular level, the diffusion rate of ions, the functioning of ion channels, the level of enzyme activity, the association-disassociation interactions between proteins and the polymerization-depolymerization reactions of cytoskeleton may be influenced by temperature change (Asztely F. et al., 1997. Extrasynaptic Glutamate Spillover in the Hippocampus: Dependence on Temperature and the Role of Active Glutamate Uptake. Neuron 18: 281-293; Sabatini Bernardo L. and Regehr W. G. 1996. Timing of neurotransmission at fast synapses in the mammalian brain. NATURE 384: 170-172.). Most modern live-cell chambers have been designed with the focus on thermal stability rather than rapid temperature change, and these chambers are therefore not suitable for studying the effects of temperature change on cells.